The present invention relates to an endoscopic apparatus with a bendable insertion section.
In general, an endoscope comprises an operating section and an insertion section extending therefrom. The insertion section has a bendable portion near its distal end portion such that its distal end can be bent in a desired direction. The bendable portion is remotely operated from the operating section by means of an operating wire. It is formed of an articulated mechanism which includes a plurality of cylinders rotatably coupled to one another.
Endoscopes have recently started to be used in the treatment of various internal organs, so that their insertion section is increasingly expected to be reduced in diameter. If the insertion section, however, is provided with a bendable portion including such an articulated mechanism as aforesaid, its diameter cannot be reduced below a fixed value. If a very thin insertion section is needed, therefore, the articulated mechanism or other bending mechanism must inevitably be removed from the section. In this case, however, the distal end portion of the insertion section cannot be bent in a desired direction.
In the field of vascular catheters, an arrangement has been proposed such that a stylet having a bendable distal end portion is inserted into a catheter, and the distal end portion of the catheter is bent by bending that of the stylet. The distal end portion of the insertion section of an endoscope may be bent by means of this mechanism. Namely, the stylet may be inserted into a channel of the insertion section so that the distal end portion of the insertion section is bent as that of the stylet is bent.
However, the bending direction of the stylet relative to the insertion section of the endoscope varies with the state of the stylet in the channel. Therefore, the bending direction of the distal end portion of the insertion section, which follows the stylet, cannot be foreseen before the stylet is bent actually. Thus, the distal end portion of the insertion section cannot accurately be bent in the desired direction. For example, it may possibly be bent in a direction such that optical fibers in the insertion section break.